The present invention relates to a paint shaker and motor therefor, particularly a paint shaker for light duty use powered by a single-action compressed-air driven motor.
Powell, U.S. Pat. No. 4,662,760, indicates that prior pneumatically driven paint shaking machines had typically been powered by single-acting air cylinder motors. It was noted that these machines had shown inadequacies in mixing metallic paints, while the more powerful, electric motor driven paint shakers had been heavy, bulky and expensive, and have the important disadvantage of being relatively unsafe in environments where combustible materials or gases are present. There has been an increasing use of metallic paints, which are difficult to mix, as the metallic elements tend to settle out relatively quickly. Another problem noted in Powell with single-action pneumatic machines is that they are generally not suitable for higher speed operation, due to problems with the valving arrangements.
As a result of these deficiencies with single-action compressed-air driven motors, Powell proposes a paint shaker employing a double-acting air driven motor controlled by a differential pressure actuated by a bistable valve assembly. However, double-action motors require at least additional machining and complexity in the cylinder and piston assembly, increasing cost and potentially decreasing reliability and durability.
The prior art in paint shakers does not point directly to an optimum motion to impart to a paint can for mixing paint. Powell and Allen, U.S. Pat. No. 5,050,996 both specifically recognize the difficulty of mixing metallic paints in particular, and teach producing an oscillatory motion about a vertical axis that extends through the paint can being shaken. However, the present inventor has recognized that such motion inevitably leaves xe2x80x9cdead spotsxe2x80x9d proximate this axis where mixing is diminished or nonexistent. Grubelic, U.S. Pat. No. 3,415,495 proposes producing a rocking motion about a horizontal axis that is located outside but still very close to the can, so that there remain areas near this axis where mixing is substantially diminished with respect to other areas. Moreover, Grubelic is silent regarding how to effectively mix metallic paint. Anderson, U.S. Pat. No. 4,893,938 proposes a more complex, compound motion that includes oscillation about a horizontal axis specifically for shaking a nail polish container.
Accordingly, there is a need for a paint shaker and motor therefor that provides the low cost, reliability, durability and safety advantages of the single-action pneumatic motors combined with a mechanism for optimally mixing paint at high speed, especially metallic paint.
The paint shaker and motor therefor of the present invention solves the aforementioned problems and meets the aforementioned need by providing a yoke having at a first end a clamp for clamping a paint can and adapted at an opposite, second end for pivotal connection to a first end of a linkage assembly for coupling the yoke to an exposed end of a linear reciprocating motor that linearly reciprocates the exposed end along a first axis. The linkage assembly converts the linear motion of the exposed end of the motor to an arcing motion. The yoke is pivotally mounted with respect to the motor so that moving the second end of the yoke along an arc also moves the first end of the yoke along a corresponding arc.
The motor includes a piston slidingly disposed in a cylinder, the piston being pivotally connected to a second end of the linkage assembly. The piston is spring biased in the cylinder toward an inlet end thereof. The cylinder includes an air inlet, for letting compressed air into the inlet end thereof, and the piston includes a passageway for ducting the compressed air to a valve having a displace able stopper, wherein the compressed air seats the stopper in the valve and thereby closes the valve. At an outlet end of the cylinder, the cylinder includes an air outlet for permitting compressed air passing the valve to exit the cylinder. The outlet end of the cylinder includes a projection against which the piston, moving toward the outlet end of the cylinder, drives the stopper so as to unseat the stopper in the valve and thereby open the valve, permitting the spring bias to return the piston toward the inlet end of the cylinder.
Therefore, it is a principal object of the present invention to provide a novel and improved paint shaker and motor therefor.
It is another object of the present invention to provide a paint shaker and motor therefor that provides the low cost, reliability, durability and safety advantages of single-action pneumatic motors.
It is still another object of the present invention to provide such a paint shaker that provides for high speed operation.
It is yet another object of the present invention to provide such a paint shaker that provides for optimally mixing the paint.
It is a further object of the present invention to provide such a paint shaker that is optimum for mixing metallic paint.
The foregoing and other objects, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the following drawings.